How high does illusion have to be,and/or how many perks do I need to effect mammoths and giants? To be more exact,how long do i have to wait until I can frenzy them? That was the whole inspiration for my using Illusion,the thought of annoying a giant/mammoth settlement into pursuing me,frenzying them near a fort or encampment,drinking an invisibility potion and watching the whole thing unfold from the safety of a nearby hill with a nice chilled bottle of black briar mead in hand. Level 35 and still no joy,how long do I have to wait?

I believe a dualcast frenzy with animage behind it should suffice. Giants and mammoths are merely 32 and 38 respectively. The calculation is as follows:

[Frenzy (14) + Animage (8) + Rage (12)] x Dualcast (2) = 68

Double casted illusion spells grants double potency so getting the double cast perk is of utmost importance to an illusionist. And getting all perks are a requirement for an illusionist.